Amounts Of Na2O Research Articles

Formation, Stability, and Crystallinity of Various Tricalcium Aluminate Polymorphs.

Tricalcium aluminate is an important phase of Portland clinker. In this paper, three polymorphs of C3A were prepared by means of the solid-state synthesis method using intensive milling of the raw material mixture which was doped with various amounts of Na2O and sintered at a temperature of 1300 °C for 2 h. The final products were evaluated through X-ray diffraction using Rietveld analysis. The effect of the Na dopant content on the change in the crystalline structure of tricalcium aluminate was studied. It was proven that the given preparation procedure, which differed from other studies, was close to the real conditions of the formation of Portland clinker, and it was possible to prepare a mixture of different polymorphs of calcium aluminate. Fundamental changes in the crystal structure occurred in the range of 3-4% Na, when the cubic structure changes to orthorhombic. At a dosage of Na dopant above 4%, the orthorhombic structure changes to a monoclinic structure. There are no clearly defined boundaries for the existence of individual C3A phases; these phases arise at the same time and overlap each other in the areas of their formation at different Na doses.

HP-PdF2-type FeCl2 as a potential Cl-carrier in the deep Earth

Abstract We report for the first time the formation of a HP-PdF2-type FeCl2 phase (space group Pa3), through high pressure-temperature (P-T) reactions in the hydrous systems (Mg0.6Fe0.4)SiO3–H2O–NaCl and FeO2H–NaCl in a laser-heated diamond-anvil cell up to 108 GPa and 2000 K. Applying single-crystal X-ray diffraction (XRD) analysis to individual submicrometer-sized grains, we have successfully determined the crystal structure of the as-synthesized FeCl2 phase, in agreement with our theoretical structure search results. In situ high P-T XRD data revealed the substitution of Cl for OH(O) in such a cubic Pa3 structure, demonstrating that this topology is a potential host for both H and Cl in the deep Earth. The chemical analysis of the recovered sample showed that the post-perovskite phase contains considerable amounts of Na2O and Fe2O3. The coexistence of the cubic FeCl2 phase and post-perovskite suggests that the lowermost mantle could be a potential reservoir of Cl. The possible presence of volatiles such as H and Cl in the deep lower mantle would impact the composition and iron valence state of the post-perovskite phase.

Competition Effects during Femtosecond Laser Induced Element Redistribution in Ba- and La-Migration Based Laser Written Waveguides.

Fs-laser induced element redistribution (FLIER) has been a subject of intensive research in recent years. Its application to various types of glasses has already resulted in the production of efficient optical waveguides, tappers, amplifiers and lasers. Most of the work reported on FLIER-based waveguides refers to structures produced by the cross-migration of alkali (Na, K) and lanthanides (mostly La). The latter elements act as refractive index carrying elements. Herein, we report the production of Ba-based, FLIER-waveguides in phosphate glass with an index contrast > 10−2. Phosphate glasses modified with the same amount of Na2O and K2O, and variable amounts of BaO and/or La2O3 were used to produce the FLIER-waveguides with Ba and or La acting as index carriers. Ba-only modified glasses show a waveguide writing threshold and light guiding performance comparable to that of La-based structures. However, mixed Ba-La glasses show a much higher element migration threshold, and much smaller compositionally modified regions. This behavior is consistent with a competition effect in the cross-migration of both elements (Ba and La) against the alkalis. Such an effect can be applied to inhibit undesired element redistribution effects in fs-laser processing applications in multicomponent glasses.

Sedimentology and Geochemistry of Quaternary Sediments and Determination of Sediment Transport, Tectonic setting in the wetland of Saghalak-Sar Rasht

Wetlands as unique, rich, and fertile ecosystems are among the most vital environments in the world. Quaternary sediments of wetlands are the main components of our environment and an essential source of clastic, organic, and chemical substances that can be caused by natural processes and erosion or created by human intervention. This article broadly deals with the grain size and geochemistry of Quaternary sediments in Saghalak-Sar as one of the wetlands in Guilan province in the north of Iran. The 74 surface and subsurface samples (from 10 core) of the sediments were graded, and sedimentationparameters of the particles (Sorting, Skewness, and Kurtosis) were determined. Also, the frequency of elements oxides and subelements oxides were determined by ICP and XRF, respectively. The sediments were classified into eight sedimentary types including Slightly Gravelly Muddy Sand, Slightly Ggravelly Sandy Mud, Sandy Mud, Gravelly Muddy Sand, Gravelly Mud, Slightly Gravelly Sandy Mud, and Gravelly Sand. On the east of the wetland (core 1 to 8), the percentage of sand is less the mud, and on the south and west of the wetland (core 9 to13), the sand is higher, indicating more energy in the south and west. Sorting of sediments is poorly to moderately sorted and the Skewness in most samples is coarse Skewed. The number of sediment content is 2 to 3, but the sand content is the majority of the samples. According to these data, the sediments are transmitted to sedimentary basins by the river or muddy streams. The comparison of the oxide elements of the above samples with upper continental crust (UCC) indicated the mean value of SiO2 (63.1%) in the wetland sediments is slightly less than the average of this oxide in the upper continental crust (66.6%), the average of CaO (0.8) less than the average of upper continental crust (except the 12 core and surface sediments sw1) and the amount of Na2O (0.8) and K2O (2.1) are less than the upper continental that indicates the destruction of plagioclases as a result of chemical weathering in the source or during the transport process. The comparison of MgO, Fe2O3, TiO2 sediment samples at different depths and upper continental crust shows that the average of MgO (1.2) is lower than the upper continental crust ten but Fe2O3 ( 7.2), TiO2 (1.2) arehigher than the upper continental crust. The decrease of CaO, Na2O, and SiO2 and the increase of Al2O3 and Fe2O3 indicate an increase in weathering during the transport process and the production of clay and aluminum oxide and iron oxide due to the decomposition of complex clays and non-clay minerals. Matching sediment samples on the two-axial diagrams of the main elements oxides, i.e., (Fe2O3+ MgO) versus Al2O3/ SiO2 and TiO2 and log (K2O / Na2O) versus SiO2, as well as the triangular diagrams of the sub-elements Zr, Th, La, and Sc, indicate that the wetland sediments are more inclined towards the range of oceanic arc islands and continental arcs, and are composed of subduction rocks.

Effects of Na2O additions to copper slag on iron recovery and the generation of ceramics from the non-magnetic residue

A novel process is proposed in this paper for a green and efficient utilization of copper slag. The basic premise involved the addition of different amounts of Na2O into molten copper slag and evaluation of the effects on the magnetic fraction and the properties of ceramics generated from the non-magnetic residue, and mechanisms of the effects were further studied by XRD, SEM, EDS, viscosity test, hysteresis loop and FTIR. The results showed that Na2O additions dropped the viscosity of the slag markedly, which promoted the growth of magnetite, but decrease quantity of magnetite due to oxidization of Fe2+ and precipitation of crystals containing Fe3+. With the addition of 4 % Na2O, solidification temperature of slag decreased from 1790 K to 1530 K, optimum iron recovery rate of 81.08 % was achieved. Na2O as flux in ceramics obviously reduced its sintering temperature and meantime decreased its bending strength because of insufficient crystallization of its main minerals. The non-magnetic residue from magnetic separation of slag with addition of 4% Na2O was converted into ceramics with a much low sintering temperature of 1268 K (995 °C) and qualified bending strength of 64.5 MPa.

Statistical Evaluation of Mechanical Properties of Slag Based Alkali-Activated Material

Slag is one of the by-products of the energy industry, which is suitable for secondary industrial processing. Although slag has been successfully used in industrial production for several decades, its use does not achieve the level of its potential. Today, to achieve a sustainable construction industry, alternative types of cement have been extensively investigated. Geopolymer is a kind of material which is obtained from the alkaline activator and it can be produced from the industrial wastes or by-products. In this study, SiO2/Na2O ratio and the amount of Na2O in activation solution parameters of alkali-activated materials were tested how they affect the strengths of hardened geopolymers from ground granulated blast furnace slag (GGBFS). Compressive and flexural strength tests were conducted, and the results were analyzed by analysis of variance (ANOVA). Strengths were tested after 7, 28, and 90 days.

Factors Affecting Compressive Strength Development in Alkali-activated Slag Concrete

Studies show that the production and use of ordinary Portland cement (OPC) is responsible for more than 5% of the global CO2 emission. Alkali-activated slag (AAS) has been studied for decades as potential alternative to OPC. Engineers are interested in understanding and quantifying the fresh properties, mechanical properties, and durability of concrete made used AAS as sole binder. This paper reviews some of the literature highlighting the factors affecting compressive strength development in AAS slag. These include water-binder-ratio, temperature, humidity, and amount of Na2O, molarity of the alkaline activator solution, and type of alkaline activator. For instance, certain studies reported that AAS concrete activated using sodium silicate solution (water-glass) produce higher 7-day and 28-day compressive strength compared to similar concrete that use 100% OPC, concrete activated using sodium hydroxide (NaOH), or concrete activated using potassium hydroxide (KOH). When NaOH is used as activator, mechanical properties of concrete improved with increase in molarity of the alkaline activator solution. Compressive strength of concrete cubes increases with increase in the amount of Na2O supplied by the activator solution but to an optimum beyond which further increase in Na2O results in decrease in compressive strength. However, the optimum amount of Na2O, often reported as percentage of total slag content, varied from one study to another, probably dependent on the type of activator used as well as the water-to-binder (w/b) ratio.

Influence of germanate anomaly on elastic, structural, and optical properties of xNa2O-(99–x)[80GeO2:20PbO]-1Er2O3 lead–germanate glasses

Abstract A sodium–lead–germanate glass system, with a composition of xNa2O-((100–y)–x)[80GeO2:20PbO]-yEr2O3 (x = 0–25 mol.%, y = 0, 1 mol.%), was prepared by melt quenching and used to investigate the effect of Na2O and Er2O3 on the germanate anomaly. The structural and optical properties of the glass samples were investigated using X-ray diffraction, Fourier transform infrared, and UV–Vis spectroscopy analyses. Elastic properties of Er2O3-doped glasses (y = 1) were studied by measuring longitudinal and shear velocities through the pulse-echo method at 5 MHz. Based on Fourier transform infrared spectroscopy analysis of Er2O3-doped glasses, the conversion of GeO4 into GeO6 indicates that the glass system possesses the germanate anomaly characteristic but has no density anomaly. Longitudinal, shear, bulk, and Young's moduli (C L, μ, K, and E, respectively) increased to their maximum values at x = 10 mol.% but decreased with increasing amount of Na2O added. This finding reveals the elastic nature of the germanate anomaly. Increase in elastic moduli indicates enhanced network rigidity of the glass system in the germanate anomaly region, where the coordination number increased with the transformation of GeO4 to GeO6. Subsequent decrease in elastic moduli (x > 10 mol.%) denotes weakened network rigidity of the glass system because of enhanced formation of non-bridging oxygen. Furthermore, analysis using bulk compression and ring deformation models reveals the nonlinear trends of K bc /K e ratio and average ring size diameter as a result of the germanate anomaly. The anomaly also influenced optical properties of both Er2O3-doped (y = 1) and Er2O3-free (y = 0) glasses, where the optical energy gap (E opt) decreased with the addition of Na2O up to 10 mol.% and slightly increased with more than 10 mol.% Na2O. By contrast, Urbach energy (E U) and refractive index (n) showed opposite trends to that of E opt. The behavior of E U indicates changes in defect concentration, which affects E opt and n.

Formation free energy of sodium stannate measured using β-β″-Al2O3 ceramic electrolyte

β-β″-Al2O3 precursor powder was successfully prepared by a solid-phase sintering method with Li2CO3, Na2CO3 (as the sources of Li2O and Na2O, respectively) and α-Al2O3 powder as the raw materials. The precursor was characterized by X-ray diffraction (XRD) and scanning electron microscope (SEM). The results indicate that the amount of Na2O in the raw materials has a great effect on the formation of β″-Al2O3 in the β-β″-Al2O3 precursor. When Na2O content is 10 wt%, the content of β″-Al2O3 phase reaches the maximum value of 86.24 wt% in the precursor. The β-β″-Al2O3 ceramic was prepared from β-β″-Al2O3 precursor powder by isostatic pressing and burying sintering process. The conductive property of the β-β″-Al2O3 ceramic was examined by electrochemical impedance spectroscopy (EIS) method, and the density was measured by the Archimedes method. The results reveal that when 10 wt% Na2O was added, the sample exhibits the best performance with the lowest resistivity of 4.51 Ω·cm and the highest density of 3.25 g·cm−3. A solid electrolyte battery of Pt|SnO2, Na2SnO3|β-β″-Al2O3|NaCrO2, Cr2O3|Pt was assembled by the β-β″-Al2O3 electrolyte tube to measure the open potential of the resulting battery, and the formation free energy of sodium stannate was calculated. In the temperature range of 1273–773 K, the relationship between formation free energy of sodium stannate and temperature was generated as follows: \(\Delta G_{{{\text{Na}}_{ 2} {\text{SnO}}_{ 3} }}^{0 } = - 1040.83 + 0.2221T \pm 7.54\).

Interpretation the Origin and Tectonic Setting of Coastal Sediments in the Northeastern of Oman Sea

This study investigates geochemistary of major and trace elements of sandstones and mudstones in the Chabahar area located of northeastern Oman Sea. In this study, 52 samples were taken from 5 sections included of Tiss, Ramin, Lipar, Gorankash and Garindar estuary. Then have been done grain size and chemical analysis using XRF and ICP AES methods in geological survey of Iran. Comparison of major elements values with the average amounts of upper continental crust indicate due to sedimentation processes or the lack of source rocks contain sodium plagioclase, the amount of Na2O and Fe2O3 in continental crust is highly depleted. Plotted geochemical data of major elements from Late Miocene-Pleistocene, age 10 mudstone and sandstone samples in east coasts of Chabahar in Makran zone, on siliciclastic rocks classification diagrams, showed that the sandstones are genus wackstone, Mudstones and shale. Values range the chemical index of alteration (CIA) and plagioclase index of alteration (PIA) respectively is from 40 to 60 and 40 to 64. However, most samples have values less than 50, suggesting a low to moderate degree of alteration (weathering) and arid to semi-arid climate during deposition in the source area. Major elements geochemistry is not useful for interpreting the tectonic setting. Discrimination plots based on assotiated trace elements, such as Ti, Zr, La, Sc and Th, show that most data located in the active continental margin field and tectonic setting have developed in active continental margin (ACM). Finally, geochemical data and using from sediments silisiclastic discriminate diagrams on the major elements in these rocks shows that the quartzose sedimentary provenance.

Potential of using granite waste as raw material for geopolymer synthesis

The main objective of this work was to investigate the potential of using granite waste (GW) as raw material for geopolymer synthesis. The disposal of GW might cause many serious environmental issues. Due to the low reactivity of this aluminosilicate material in its natural state, GW was activated through alkali fusion with different amounts of sodium hydroxide. Fused materials obtained were then used to synthesize geopolymers at room temperature using sodium silicate as activator. The products were characterized using compressive strength, water resistance, XRD, IR spectroscopy and SEM/EDS analyzes. The results showed that the reactivity of GW is improved by alkali fusion method. The amount of reactive phase significantly increases with the amount of Na2O during the pre-activation process. Compressive strength results of geopolymer mortars are varying between 6.25 and 40.5MPa depending on the amount of Na2O used during the alkali fusion process.

Removal of Boron and Phosphorus from Silicon Using CaO-SiO2-Na2O-Al2O3 Flux

A combination of solvent refining and flux treatment was employed to remove boron and phosphorus from crude silicon to acceptable levels for solar applications. Metallurgical grade silicon (MG-Si) was alloyed with pure copper, and the alloy was subjected to refining by liquid CaO-SiO2-Na2O-Al2O3 slags at 1773 K (1500 °C). The distribution of B and P between the slags and the alloy was examined under a range of slag compositions, varying in CaO:SiO2 and SiO2:Al2O3 ratios and the amount of Na2O. The results showed that both basicity and oxygen potential have a strong influence on the distributions of B and P. With silica affecting both parameters in these slags, a critical $$ P_{{{\text{O}}_{2} }} $$ could be identified that yields the highest impurity pick-up. The addition of Na2O to the slag system was found to increase the distributions of boron and phosphorus. A thermodynamic evaluation of the system showed that alloying copper with MG-Si leads to substantial increase of boron distribution coefficient. The highest boron and phosphorus distribution coefficients are 47 and 1.1, respectively. Using these optimum slags to reduce boron and phosphorus in MG-Si to solar grade level, a slag mass about 0.3 times and 17 times mass of alloy would be required, respectively.

Using chemometric methods for overlap correction of sodium-zinc spectral lines generated by wavelength dispersive X-ray fluorescence in mineral samples

Partial least squares, principal component regression and support vector machine multivariate methods were used for overlap correction of sodium–zinc (Na(Kα)–Zn(Lα)) spectral lines generated by means of wavelength dispersion X-ray fluorescence (WDXRF) combined with standard-less software (IQ+) technique for the analyses of mineral samples. This methodology uses one scan channel using PX1 analyzer crystal, 550-µm collimator, flow detector (Ar + CH4), and rhodium (Rh) tube for determination of Na and Zn in mineral compositions in minimum time. The calibration matrix was made up of 35 samples containing different amounts of Na2O and ZnO. The considered concentration ranges were 0–5% for both Na2O and ZnO. The values for 2θ angle were recorded between 25° and 29.9° at every 0.1°. Variable tube powers (kV − mA) were used to investigate the effect of tube power on the analyses of elements. The validation of the multivariate methods was realized by analyzing soil samples. Atomic absorption and flame photometry methods were used as reference methods for analyzing Zn and Na in the soil samples, respectively. The results of using chemometric methods, WDXRF (standard-less software) and reference method determined partial least squares and support vector machine models obtained more acceptable results for Na2O in presence of ZnO than those of WDXRF (standard-less software). Copyright © 2013 John Wiley & Sons, Ltd.

Fabrication of (K, Na)NbO 3 glass–ceramics and crystal line patterning on glass surface

Crystallization behavior of (30− x)K 2O– xNa 2O–25Nb 2O 5–45SiO 2 (KNNS; x = 0, 5, 10, 20 and 30) (mol%) glasses was clarified and perovskite-type nonlinear optical (K, Na)NbO 3 (KNN) crystals were synthesized by using a conventional glass–ceramics method. It was found that Na 2O amounts over around x = 10 mol% were necessary to form perovskite-type KNN crystals showing second-harmonic generations. The substitution of K + and Na + ions was confirmed from X-ray diffraction (XRD) analysis. A continues-wave of Yb:YVO 4 fiber laser (wavelength: 1080 nm) was irradiated onto CuO doped KNNS; x = 10 (Cu–KNNS) surface. The absorption coefficient of this Cu–KNNS glass was determined to be α = 5.0 cm −1. Perovskite-type KNN crystals were patterned in the condition of the laser power of >1.20 W and the laser scanning speed of S = 7 μm/s, and their structure was determined by Raman scattering spectra and XRD analysis.

Ash from a pulp mill boiler—Characterisation and vitrification

The physical, chemical and mineralogical characterisation of the ash resulting from a pulp mill boiler was performed in order to investigate the valorisation of this waste material through the production of added-value glassy materials. The ash had a particle size distribution in the range 0.06–53 μm, and a high amount of SiO 2 (∼82 wt%), which was present as quartz. To favour the vitrification of the ash and to obtain a melt with an adequate viscosity to cast into a mould, different amounts of Na 2O were added to act as fluxing agent. A batch with 80 wt% waste load melted at 1350 °C resulting in a homogeneous transparent green-coloured glass with good workability. The characterisation of the produced glass by differential thermal analysis and dilatometry showed that this glass presents a stable thermal behaviour. Standard leaching tests revealed that the concentration of heavy metals in the leaching solution was lower than those allowed by the Normative. As a conclusion, by vitrification of batch compositions with adequate waste load and additive content it is possible to produce an ash-based glass that may be used in similar applications as a conventional silicate glass inclusively as a building ecomaterial.

Hydration and hydration products of two-phase Portland cement clinker doped with Na2O

Alkalis are important minor constituents of ordinary Portland cement clinker. Na2O, in particular, is incorporated into the aluminate phase and alters its crystal structure. For this study, well defined Portland cement clinkers consisting of alite and aluminate doped with different amounts of Na2O were used. Isothermal conduction calorimetry of cements made from this clinker revealed that doping with Na2O activates the initial heat evolution of the clinker during the initial hours. It also influences the main reaction. In situ X-ray diffraction for monitoring cement hydration demonstrates that the dissolution of C3A and gypsum is accelerated by the incorporation of Na2O. The formation of crystalline ettringite and monosulphate during the first few hours of hydration is delayed. After 90 days of hydration, most of the C3A has reacted to monosulphate, detectable by differential scanning calorimetry, scanning electron microscopy and 27Al nuclear magnetic resonance. An increase of the Na2O content brought about less ettringite in the hydrated samples and changed the morphology of monosulphate to thinner and smaller hexagonal plates.

Degradation behaviour of borosilicate glass: some studies

PurposeTo study the degradation behaviour of borosilicate glass, which is suitable for hermetic sealing with Molybdenum and Kovar (Fe/Co/Ni) alloys, as a function of concentration and temperature in both acidic and alkaline media for long durations, up to 160 h.Design/methodology/approachThe degradation (weight loss in mg/cm2 of the glass sample) was determined by immersing the glass sample in HCl and NaOH solutions at different temperatures for different periods extending up to 300 h. The damage to the glass surface was seen under an optical microscope and the chemical species on the corroded surface were identified by electron spectroscopy for chemical analysis.FindingsThe borosilicate glass, having the nominal composition 0.70 SiO2, 0.039 Na2O, 0.028 K2O, 0.21 B2O3, 0.01 Al2O3 was synthesized by melt and quench techniques. Degradation (corrosion) behaviour of this glass was investigated by immersing glass samples in 5 and 10 per cent HCl and 5 per cent NaOH solutions at different temperatures up to 90°C, for different periods and measuring dissolution rate (weight loss in mg/cm2 of the sample). Dissolution rates were found to be 5.47 mg/cm2 and 46.77 mg/cm2 in 5 per cent NaOH at 60 and 90°C, respectively, whereas they were comparatively low (2.59 and 5.80 mg/cm2 at 60 and 90°C, respectively, in 5 per cent HCl medium) after 160 h of total immersion period. The plot of dissolution rates against the temperatures showed the nonlinear behaviour at higher temperatures, probably due to the change in mechanism of corrosion. XPS studies exhibited the chemical species on the corroded surfaces. The optical microscopy of the corroded surface revealed that the corrosion mechanisms were different in acid and alkali media.Research limitations/implicationsThe degradation behaviour of borosilicate glass having a specific composition has been investigated as a function of concentration and temperature in both acid and alkaline media. The mixed alkali effect on the degradation behaviour may be studied by varying relative amount of Na2O and K2O in the glass composition.Practical implicationsThe glass composition under the present study has been used for fabrication of matched type glass‐to‐metal (GM) seals with kovar alloy. In this respect the present study is significant in deciding the environmental conditions for its use.Originality/valueThe degradation behaviour of borosilicate glass having alkali and alkaline earth metal oxides has been investigated as a function of concentration and temperature in both acid and alkali media. The findings in this paper have the potential implications in deciding the environmental conditions for use of GM seals fabricated using this glass.

Differences in densification behaviour of K- and Na-feldspar-containing porcelain bodies

Porcelain bodies fabricated from triaxial mixtures of clay, quartz and feldspar with different amounts of Na 2O and K 2O were investigated to study their densification behaviour on thermal treatment at which the bodies achieve full vitrification. The high temperature dilatometric study has shown a distinct behaviour in their densification rate. The degree of vitrification of the densified samples and samples separately heated at different temperatures was determined by measuring the shrinkage, bulk density (BD), percent water absorption (%WA) and flexural strength. It was found that Na-rich feldspar containing body composition achieve full vitrification at lower temperature compared to K-rich feldspar containing composition with improved flexural strength. Differential thermal analysis–thermogravimetric analysis (DTA–TGA) confirms similar reaction steps for both the compositions up to 1000 °C, beyond which feldspar forms eutectic melt and starts reacting. As the purity of raw materials has a strong influence on the colour of the fired bodies, the bodies were also subjected to colour measurement and their differences in whiteness also compared, and is discussed in this paper. The scientific and technological importance of such vitrified porcelain products has also been touched upon, highlighting their industrial application.

Oxygen and phosphorus coordination around iron in crystalline ferric ferrous pyrophosphate and iron-phosphate glasses with UO2 or Na2O

Fe K-edge x-ray absorption fine-structure (XAFS) measurements were performed on glass samples of (Fe3O4)0.3(P2O5)0.7 with various amounts of Na2O or UO2. Near-edge and extended XAFS regions are studied and comparisons are made to several reference compounds. We find that iron in the base glass is ∼25% divalent and that the Fe2+ coordination is predominantly octahedral, while Fe3+ sites are roughly split between tetrahedral and octahedral coordinations. Also, we measure roughly one Fe–O–P link per iron. Substitution of Na2O or UO2 up to 15 mol% primarily affects the first Fe–O shell. The results are compared to data from the related material Fe3(P2O7)2.

Physical chemistry of aluminosilicate gels. Part 2 Influence of the batch molar ratio SiO 2/Al 2O 3 on chemical composition of the gels

The influence of the batch (b N: N = I, II) molar ratio. Y=[SiO 2] b N /[Al 2O 3] b N , and order of mixing of aluminate and silicate solutions (A: sodium silicate to sodium aluminate solution; B: sodium aluminate to sodium silicate solution) on the distributions of Na, Al and Si between the solid (S) and the liquid (L) phase of the sodium aluminosilicate hydrogels prepared at the constant batch concentrations of SiO 2, i.e. [SiO 2] bI = 0.20505 mol dm −3 [System I(A,B)]; [SiO 2] bII = 0.410l mol dm −3 [System II(A.B)], were investigated by measuring the concentrations of Na. Al and Si in both solid and liquid phase by atomic absorption spectrometry. It was found that the amounts of Na 2O and Al 2O contained in the solid phase are directly proportional to the batch concentration [Al 2O 3] b N , and inversely proportional to the batch concentration [Na 2O] b N , i.e. both the [Na 2O] S and [Al 2O 3] S are linear functions of 1/( Y[Na 2O] b N ). On the other hand, logarithms of the molar ratios [Al 2O 3] S/[Al 2O 3] L, [SiO] S/[SiO 2] L and [SiO 2] L/[Al 2O 3] L are linear functions of the batch molar ratio 1/ Y=[Al 2O 3] b N /[SiO 2] b N , while the molar ratio [SiO 2] S/[Al 2O 3] S of SiO 2 and Al 2O 3 in the precipitated amorphous aluminosilicate is in linear relationship with the batch molar ratio 1/ Y in the region 2< Y<32. Based on these interrelations, it was found that the equation [SiO 2] S/[Al 2O 3] S-0.18 ln([SiO 2] L/[Al 2O 3] L) = 2.554 satisfactorily describes the equilibrium distribution of SiO 2 and Al 2O 3 between the solid and the liquid phase of the investigated aluminosilicate hydrogels.